锂离子电池硅/碳纳米管/石墨烯自支撑负极材料研究

doi:10.15541/jim20160520

摘要/Abstract

摘要：

通过真空驱动自组装法及蒸汽处理得到结构疏松的硅/碳纳米管/石墨烯自支撑负极材料(Si/CNTs/GP)。纳米硅颗粒(50 nm)为活性物质, 均匀分布在石墨烯片层结构中间; 石墨烯作为碳基体, 通过自组装构筑形成二维导电网络; 碳纳米管(CNTs)具有超高导电性和良好的力学强度, 它通过吸附作用均匀分布在石墨烯基体上形成导电的支撑网络结构。经过蒸汽处理后, 石墨烯层间距明显增大, 层与层之间不再是紧密堆叠的结构, 而是形成一种疏松、褶皱、内部空隙丰富的片层结构。Si/CNTs/GP负极材料中丰富的内部空穴和贯穿孔洞, 提供了材料很高的比表面积, 能有效提高电解液对材料的浸润性, 极大缩短了离子传输距离。同时这些内部空穴也有效缓冲硅充放电时的体积膨胀, 提高了材料的结构稳定性和电化学性能。该负极材料在4 A/g的大电流密度下容量维持在600 mAh/g, 表现出良好的大电流循环稳定性能。

关键词: 石墨烯, 硅, 锂离子电池, 自支撑, 蒸汽处理

Abstract:

Porous 2D Silicon/CNTs/Graphene free-standing composites were prepared via a solution-based self-assembly process with vapor post-treatment and applied as anodes for lithium-ion batteries. Silicon nanoparticles (~50 nm) as active materials were uniformly embedded between graphene sheets without agglomeration. Graphene was used as electrical conductive carbon matrix to form a 2D conductive network for electrons. CNTs, with high electrical conductivity and mechanical strength, formed into a scaffold along with graphene to enhance the conductivity and mechanical properties of the carbon matrix. After vapor post-treatment, CNTs supported graphene film transferred from a tightly stacked film to a loose packed porous film. The porous structure of this free-standing composite anode provides large internal space to accommodate volumetric changes and provide abundant channels for diffusion of Li⁺, fast electron transport and easy penetration of electrolyte. The composites exhibite an outstanding rate performance and cyclic stability, delivering a capacity of 600 mAh/g at 4/A g and 1010 mAh/g after 100 cycles at 0.1 A/g. They also show high structure and mechanical stability after cycle test. It provides an exciting pathway to the rational design and fabrication of silicon anode and 2D graphene matrix for applications in lithium-ion batteries.

Key words: graphene, silicon, lithium-ion battery, free-standing, vapor post-treatment

中图分类号:

TM911
O613

白雪君, 刘婵, 侯敏, 王彪, 曹辉, 付俊杰. 锂离子电池硅/碳纳米管/石墨烯自支撑负极材料研究[J]. 无机材料学报, 2017, 32(7): 705-712.

BAI Xue-Jun, LIU Chan, HOU Min, WANG Biao, CAO Hui, FU Jun-Jie. Silicon/CNTs/Graphene Free-standing Anode Material for Lithium-ion Battery[J]. Journal of Inorganic Materials, 2017, 32(7): 705-712.

图/表 12

图1 Si/CNTs/GP负极材料制备过程中结构变化流程图

Fig. 1 Schematic illustration of synthesis of Si/CNTs/GP composites

图2 氧化石墨烯复合PDDA前、后在不同酸碱度下的Zeta电位

Fig. 2 Zeta potential of GO and PDDA-GO at different pH

图3 Si、CNTs、Si/GP、Si/CNTs/GO和Si/CNTs/GP负极材料的 XRD图谱

Fig. 3 XRD patterns of Si, CNTs, Si/GP, Si/CNTs/GO, and Si/CNTs/GP composite film

图4 CNTs、Si/GP、Si/CNTs/GO和Si/CNTs/GP负极材料的拉曼图谱

Fig. 4 Raman spectra of CNTs, Si/GP, Si/CNTs/GO and Si/CNTs/GP composite film

图5 CNTs、Si/GP、Si/CNTs/GO和Si/CNTs/GP负极材料的XPS图谱

Fig. 5 XPS spectra of CNTs, Si/GP, Si/CNTs/GO, and Si/CNTs/GP composite(a) Survey spectra; (b) High resolution C1s spectra; (c) High resolution N1s spectra; (d) High resolution Si2p spectra

图6 Si、GP、Si/GP 和 Si/CNTs/GP-(1, 2)负极材料在空气气氛中的热失重曲线

Fig. 6 TGA curves of Si, GP, Si/GP, and Si/CNTs/GP-(1, 2) composites in air

图7 材料的表面和截面FESEM照片(a,b,c) Si/GP、(d, e, f) Si/CNTs/GO、(g, h, i) Si/CNTs/GP, 内图为实物图

Fig. 7 Surface and cross-section FESEM images of (a,b,c) Si/GP, (d, e, f) Si/CNTs/GO, and (g, h, i) Si/CNTs/GP with digital photo inset

图8 Si/CNTs/GP-1负极材料的电池循环伏安曲线

Fig. 8 CV curves of Si/CNTs/GP-1 composite

图9 Si/GP 和 Si/CNTs/GP-(1, 2)负极材料的电池倍率循环性能

Fig. 9 Rate capacity of Si/GP and Si/CNTs/GP-(1, 2) at various rates as marked

图10 Si/GP(a, b)和Si/CNTs/GP-1(c, d)负极材料倍率循环后负极极片的FESEM照片及EDS能谱

Fig. 10 FESEM images of (a, b) Si/GP and (c, d) Si/CNTs/GP-1 anode after rate cycling test, with EDS inset

图11 Si/GP 和 Si/CNTs/GP-(1, 2)负极材料倍率循环后的交流阻抗图

Fig. 11 Electrochemical impedance spectra of Si/GP and Si/CNTs/GP composites after rate cycling test The inset is the equivalent circuit

表1 Si/GP和Si/CNTs/GP-(1, 2)负极材料交流阻抗拟合数据

Table 1 EIS fitting results of Si/GP and Si/CNTs/GP-(1, 2) electrodes

Sample	R_s/Ω	R_SEI/Ω	R_ct/Ω
Si/GP	3.5	22.1	25.2
Si/CNTs/GP-1	2.5	8.7	19.9
Si/CNTs/GP-2	2.0	1.7	18.1

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